Cell Signal Monitor - Cell Signal Monitor is an advanced network monitor that helps you to watch the state of cellular network by gathering data about cell towers. The app supports GSM, UMTS and LTE networks. There is a Free edition with adds.

NetSpeedMonitor - NetSpeedMonitor is a lightweight Network Monitoring Toolbar for your Windows Taskbar

OpenSignal - Mobile analytics and insights on wireless connectivity from Opensignal, the independent global standard for understanding the true state of the world's mobile network.

NetTraffic - Essential network bandwidth monitor.

NetMonster - NetMonster is a networking app by Michal Mrocek that comes up with features to enable you to get detailed information about your current network right on your mobile phone screen.

FreeMeter - Monitor network bandwidth (C#.NET 2k/XP+). Desktop and Systray graph.